Speed for rotational axis.

[danut1234]

Hi, i don't understand why the command from below respect the feed speed when the axis is configured as Cartesian, and does not respect the feed speed when configured as rotational axis, and goes max speed for that axis. I understand that Cartesian is in mm units and rotational is degrees... but it does not respect them. Homing the rotational axis respects the speed.

UC100.AddLinearMoveP(null, null, null, 20, null, null, 10, 1);

What i am doing wrong?

[danut1234]

If i add another parameter (in this example Z), like the one below, it works, respects the speed. The A axis when configured as rotational axis and a command is sent only for A axis (i did not tested B axis) the speed is not respected, and it goes at maximum speed from the settings.
Is this normal?


UC100.AddLinearMoveP(null, null, 20, 20, null, null, 10, 1);

[dezsoe]

When you set the axis to rotational then it follows the other axes. This means that the rotational movement happens while the other axes move, it follows them.

The rotational mode for the axis will not switch it into degrees. If you want to program any of the axes in degrees then you have to set the steps/units value to the steps/1 degree. (Steps/full rotation divided by 360.)

[danut1234]

thank you

i am almost sure that i have missed something...

[danut1234]

The problem are not the degrees, mm, or other units. Although there is a variable in the Axis settings that makes it possible for the board to return a value for rotational axis in the range of 0-360
I don't understand the concept of "following the other axes" can you explain?

UC100.AddLinearMoveP(null, null, null, -20, null, null, 100, 1);
and
UC100.AddLinearMoveP(null, null, null, -20, null, null, 0.0001, 1);
makes a movement at the same speed, the maximum speed from the settings for A axis.
do you understand the problem?
Jog-ing A axis configured as rotational works normaly.

[dezsoe]

I'll try to explain it another way. You have the standard 3 axes and a rotary, the A. You want to engrave a spiral: X has to move 100mm and A 90 degrees. In standard mode when you start G1 X100 A90 F100 it will move very slowly, because it calculates the speed with both X and A. In rotary mode the X will move at 100 mm/min and while the X moves the A will turn 90 degrees, but the speed of A is not set by the F. The A follows the other (not rotary) movements. That is why A will run at max. speed if only the A is moved, because it has to do its movement in 0s, because there's no not-rotary movements.

[danut1234]

So it was made intentionally that Rotary axis do not respect the commanded speed? The speed parameter is just ignored? The Rotary axis does not need to go to the commanded position in 0S, it needs to go with the commanded speed in how many seconds it needs.

[dezsoe]

It has to move to the commanded position while the other axes move. So the time is calculated from the other movements.

[hmnijp]

So it was made intentionally that Rotary axis do not respect the commanded speed? The speed parameter is just ignored? The Rotary axis does not need to go to the commanded position in 0S, it needs to go with the commanded speed in how many seconds it needs.

maybe you should look at the G93?
it was invented to avoid discrepancies between feeds in mm and in degrees when using rotary axes. In G93 mode, the parameter F is not the speed, but the time during which the movement must be made in each line

[smouritsen]

I came here facing the same question. I can't believe you can't control the speed of the a axis by itself. In my case I want to cut a groove in a cylinder, so no movement in the x direction, but 360 degrees rotation of the a axis. It seems really odd to me that I would have to control the speed of this operation by setting the max speed in settings. In Mach 3 I could just do G1 A360 F10 for example, and it would respect the speed parameter. Is this really not possible with UCCNC? Or am I reading this thread wrong?